As a material that provides a high quality image with image stability at a low price, a silver halide photographic light-sensitive material has been widely used until today. Demands for advances in image quality, stability of quality and productivity by users have been remarkably increasing in recent years. As to the demands for advances in image quality, it is wanted to improve pure whiteness, color reproduction, sharpness, etc. As to the demands for advances in quality stability, it is necessary to improve production stability of a light-sensitive material, storage stability in the unexposed state and performance stability during developing processing. As to the improvement in productivity, advances in processing speed are wanted.
In photographic light-sensitive materials for direct view such as a color paper and a color reversal, color reproduction is particularly important. For improvement of color reproduction, first of all it is essential that dyes formed by a coupling reaction between a dye-forming coupler (hereinafter sometimes referred to simply as “a coupler”) and an oxidized product of a developing agent have substantially no unwanted absorption and they are excellent in absorption characteristics. In addition, it is important to reduce a residual color owing to remaining sensitizing dyes and/or dyes for prevention of irradiation (irradiation-neutralizing dyes) and also fogging.
Further, in order to form a dye exhibiting a satisfactory color reproduction, performance stability during developing processing is important. Particularly from the viewpoint of advances in productivity, there is a demand for technology realizing reduction in both an amount of silver halide emulsion that is used in the silver halide color photographic light-sensitive material and a layer-thickness of a light-sensitive material, resulting in a thinner layer light-sensitive material.
As the coupler that forms a cyan dye having a low secondary absorption, phenol-based cyan couplers described in U.S. Pat. Nos. 5,686,235 and 5,888,716 are known. However, because the cyan couplers described in these patents are low in activity, they need a large amount of a high boiling point organic solvent, and it is necessary to use a large amount of a silver halide emulsion for compensation of a colored density. Further, because said cyan dye has a low secondary absorption, it is necessary for compensation of a gray density to use larger amounts of a yellow dye-forming coupler and a magenta dye-forming coupler than those required when other types of cyan dye-forming coupler are used. Under such circumstances, there is a demand for technologies that enable to improve both color reproduction and a rapid processing suitability.
In a silver halide photographic light-sensitive material (hereinafter, sometimes referred to simply as “a light-sensitive material”) for subtractive color photography, a color image is formed by dyes of three primary colors of yellow, magenta and cyan. In the color photography that uses the current p-phenylenediamine color-developing agent, acylacetoanilide-based compounds are conventionally used as a yellow coupler to form yellow-image.
The yellow coupler that is used in a light-sensitive material for direct view such as a color paper is set importance on hue and fastness property of a dye obtained from the coupler. From this reason, mainly pivaloyl acetoanilide-based couplers have been used until today. However, a hue obtained from these color-forming couplers (hereinafter, sometimes referred to simply as “coupler”) extends to an undesirable longer wavelength region, which renders it difficult to obtain a yellow color that is high in color purity. Further, owing to a lower molar absorbance of said yellow dyes than those of magenta dyes or cyan dyes, it is necessary for obtaining a desired density to use larger mounts of both the yellow coupler and the silver halide emulsion than the case of using a magenta coupler or a cyan coupler. Further, the current yellow dyes are not satisfactory to the image storage stability under the conditions of high temperature and high humidity, or the conditions of light irradiation.
In order to solve such the problems, the acyl group and the anilido group were improved. Recently, as improved couplers of the conventional acylacetoanilide-series, there are proposed, for example, 1-alkylcyclopropanecarbonyl acetoanilide-series compounds, described in JP-A-4-218042 (“JP-A” means unexamined published Japanese patent application); cyclomalonic acid diamide-type couplers, described in JP-A-5-11416; pyrrole-2- or 3-yl- or indole-2- or 3-yl-carbonylacetoanilide-series couplers, described in, for example, European Patent Nos. 953870A1, 953871A1, 953872A1, 953873A1, 953874A1 and 953875A1. The dyes formed from these couplers were improved in terms of both hue and molar extinction coefficient, compared with the conventional ones. However, they are still deficient in image stability. Further, owing to their complicated chemical structure, the synthesis route became longer, and consequently cost of the couplers became higher, causing a practical problem.
In addition, U.S. Pat. No. 3,841,880, JP-A-52-82423 and JP-A-2-28645 propose acetate ester-series and acetoanilide-series couplers to which 1,2,4-benzothiadiazine-1,1-dioxide is bonded. However, these couplers are low in color-forming property, they are insufficient in extinction coefficient of a resultant dye, and they are inferior in sharpness at the foot portion of a peak in interest of the absorption curve at the longer wavelength side. Therefore, improvement of these problems is desired.
On the other hand, in the field of color print in recent years, there are demands for advances in efficiency of shortening a time ranging from print exposure to color development processing, mainly from the purpose of enhancing productivity at labo. Examples of the means for improving performance obtained by a color photographic light-sensitive material with a color development processing include:    (1) Reduction in a coating amount of organic materials by means of, for example, employing a coupler that forms a dye having a large molar extinction coefficient,    (2) Reduction in a coating amount of a silver halide emulsion attendant upon (1),    (3) Reduction in both a coating amount of a hydrophilic binder and a thickness of the entire photographic constitutional layers attendant upon (1),    (4) Employment of a coupler having a high activity, and    (5) Employment of a silver halide emulsion that can be processed at a high developing speed.
In order to enhance a suitability of a light-sensitive material to advances in ultra-rapid processing of color development and desilvering, efforts to reduce a coating silver amount of the light-sensitive material have been made in the field of the art by means of, for example, employment of a coupler that can form a dye having a high molar extinction coefficient. However, the dyes obtained from the current yellow couplers used in a blue-sensitive emulsion layer are still unsatisfactory to the points of not only a molar extinction coefficient but also a coupling activity. Accordingly, in order to enhance productivity in a development processing such as rapidity and processing stability, it is desired to develop a new yellow coupler that forms a dye image exhibiting a superior absorption characteristic and high absorbance, and at the same time good fastness properties to light and heat.
Further, recently digitalization has been remarkably widespread in the field of a color print using a color photographic printing paper. For example, a digital exposure system in which laser scanning exposure is used, has been rapidly spreading in comparison with an ordinary analog exposure system in which printing is directly conducted from a processed color negative film with a color printer. Such digital exposure system is characterized in that a high image quality is obtained by image processing, and greatly contributes to improving qualities of color print using a color photographic printing paper. Further, according to the rapid spreading of digital cameras, it is also an important factor that a color print with a high image quality is easily obtained from these electronic recording media. It is believed that solving these problems will rapidly spread further.
On the other hand, technologies of another color print process such as an ink jet process, a sublimation process and a color xerography are advanced. Now, each of them enjoys a reputation for a photographic image quality, and they are obtaining acknowledgement as a popular color print process.
Among these color print processes, a digital color print process using a color photographic paper is characterized in a high image quality, a high productivity and a high fastness property of the image. Moreover, demands for further advances in the above-mentioned characteristics, whereby a photograph showing a higher image quality can be more simply produced with a low cost, have been increasing from customers. In particular, if it is realized that a recording medium for a digital camera is received from a customer at the shop and a print with a higher image quality is finished within about several minutes, then and there the print with the recording medium is returned to the customer, a superiority of the color print process using a color photographic paper to other color print processes will still more increase. From these points, it is extremely important that the color photographic paper is provided with a low cost, higher productivity and better rapid processing suitability than before.
Researches in wide aspects including improvement of a coupler and a silver halide emulsion to be used have been made to give a high productivity and an ultra-rapid processing suitability with a low cost to the color photographic paper. As the yellow couplers, acyl acetic acid anilide compounds have been used until today. However, because these couplers are low in chromophoric activity and dyes from these couplers are low in molar extinction coefficient, it is necessary to use a large amount of a coupler and a silver halide emulsion so that a desired developed color density can be obtained.
As the silver halide emulsion for use in a color photographic paper, a silver halide emulsion having a high silver chloride content has been used from a demand for a rapid processing. It is believed that such a high silver chloride emulsion shows a high development progressive speed and a good stability to a variation of the processing factors, because a development-inhibiting material such as Br ions and I ions is neither released from the emulsion at the development processing nor accumulates in a developing solution. Accordingly, it was difficult from a general knowledge to expect that stability would be improved by the incorporation of Br and I in a specific state (mode) in a silver halide emulsion.
It is disclosed in JP-A-58-95736, JP-A-58-108533, JP-A-60-222844, JP-A-60-222845, JP-A-62-253143, JP-A-62-253144, JP-A-62-253166, JP-A-62-254139, JP-A-63-46440, JP-A-63-46441, JP-A-63-89840, U.S. Pat. Nos. 4,820,624, 4,865,962, 5,399,475, and 5,284,743 that a high sensitivity can be obtained by the incorporation of a localized phase formed by the silver halide grains having a high silver bromide content in the various states (modes) in an emulsion composed of silver halide grains having a high silver chloride content.
U.S. Pat. Nos. 5,726,005 and 5,736,310 each disclose that high sensitivity and reduction of high illumination intensity reciprocity law failure are attained by an emulsion composed of high silver chloride grains having a I concentration maximum at the near surface of the grains.
It is disclosed in Example of European Patent 0,928,988A that an emulsion having improved reciprocity law failure, dependence on temperature at the time of exposure and fluctuation in photographic performance by pressure can be obtained by the incorporation of a specific compound in grains having a side length of 0.218 μm, and an equivalent-sphere diameter of about 0.27 μm, said grains containing a I band formed at the time where 93% of grains have been formed.
Doping of iridium is known as a means of improving a high illumination intensity reciprocity law failure of the high silver chloride emulsion, resulting in hard gradation even under a high illumination. For example, JP-B-7-34103 discloses that a problem of the latent-image sensitization can be solved by the providing of a localized phase having a high silver bromide content and iridium doped therein. U.S. Pat. No. 5,691,119 discloses a means of hard gradation enhancement of the high illumination intensity gradation in a preparation method of an emulsion composed of silver halide grains containing a localized phase having a high silver bromide content.
However, none of these publications teaches that the above-mentioned silver halide emulsions are able to solve a problem of the fluctuation in yellow density due to the variation of processing factors that is caused when a color photographic light-sensitive material containing a particular yellow dye-forming coupler is subjected to an ultra-rapid processing.